feat(languageSchema): split value to extract only language and not country code

pt-BR becomes pt
en-US becomes en

src/schema.ts

@@ -42,7 +42,7 @@ const fileSchema = z.custom<File>((value) => value instanceof File);
 const percentageSchema = z.coerce.number().int().gte(1).lte(100);
 
 const languageSchema = z.string().transform((val, ctx) => {
-  val = val.toLowerCase();
+  val = (val.toLowerCase()).split('-')[0]; // pt-BR -> pt
   if (!ISO6391.validate(val)) {
     ctx.addIssue({
       code: z.ZodIssueCode.custom,